Description and History

NPL Listing History

NPL Status: Proposed

Proposed Date: 08/21/97

Final Date:

Deleted Date:

The Palos Verdes Shelf (PV Shelf) site is a large area of DDT- and PCB-contaminated sediment located in the ocean off the coast of the Palos Verdes peninsula near Los Angeles, California. The offshore site stretches from Point Fermin in the southeast to Palos Verdes Point in the northwest, a distance of about 15 kilometers. The shelf varies in width from approximately 1 to 6 km, begins in water depths of 30 meters and gently slopes to water depths of approximately 70 to 100 meters, where the shelf breaks. At the shelf break, the slope increases to 13 to 18 degrees, leading to the ocean floor at depths of over 800 meters.

DDT is present in the Palos Verdes sediments largely as a result of wastewater discharges from the former Montrose Chemical Corporation DDT manufacturing plant in Torrance, California, which operated from 1947 to 1983. Wastewater containing significant concentrations of DDT was discharged from the Montrose plant to local sewers and conveyed to the Joint Water Pollution Control Plant (JWPCP) owned and operated by the County Sanitation Districts of Los Angeles County. Wastewater from the JWPCP is discharged to the Pacific Ocean through submarine outfalls located off White Point on the Palos Verdes peninsula. It is estimated that over 1,700 tons of DDT were discharged by the JWPCP from the late 1950s to the early 1970s.

PCBs from several sources in the greater Los Angeles area were also discharged into the sewer system and released through the White Point outfalls. Much of the DDT and PCBs released through the outfalls settled out on the ocean floor along with the suspended solids and other contaminants in the JWPCP effluent, forming what is referred to as an effluent-affected sediment layer. The DDT- and PCB-contaminated sediment deposit covers portions of both the continental shelf (the Palos Verdes Shelf) and continental slope off the Palos Verdes peninsula and ranges in thickness from 5 centimeters (cm) to greater than 60 cm. The total volume of the effluent-affected sediment deposit is over 9 million cubic meters, with approximately 70% of this volume on the continental shelf (i.e., in water depths less than 100 m). In its 1994 report, the U.S. Geological Survey (USGS) characterized an area of 44 km2 (17 sq. miles) on the PVS with elevated levels of DDT and PCBs in surface sediments. Subsequent data showed that the effluent-affected DDT- and PCB- contaminated sediments covered a larger area, and EPA expanded the PVS study area to include sediments from Point Fermin in the southeast to the southern edge of the Redondo canyon, northwest of the Palos Verdes peninsula. EPA's evaluation of potential cleanup actions is focusing on the areas of highest contamination.

Historically, the waters of the Palos Verdes Shelf have been used extensively by both sport and commercial fishermen - sport fishermen, anglers from party boats, private boats, rocky intertidal areas and sandy beaches. Other activities in this coastal area include boating, swimming, windsurfing, surfing, scuba diving, snorkeling and shellfishing.

Contaminants and Risks

Contaminated Media

Sediments and Surface Water

The area of highest DDT and PCB contamination in sediment is located roughly 2 km offshore and extends westward from the outfalls approximately 5 km along the shelf. Because the most significant discharges of DDT and PCBs to the Palos Verdes Shelf ceased in the early 1970s, the most contaminated sediments have gradually been covered over, primarily by solids discharged through the outfalls and by solids eroded from the nearby Portuguese Bend landslide area. The depth in the sediment column to the maximum concentration of DDT is greater than 40 cm on parts of the shelf but is commonly less than 10 cm on the slope. The maximum concentration of DDT exceeds 200 ppm near the outfall pipes; concentrations in excess of 50 ppm extend up to 4 km to the west of the outfalls. The distribution of PCBs follows a similar pattern, although concentrations are about an order of magnitude lower than the DDT.

High levels of DDT and PCBs are found in the active biologic zone of the Palos Verdes Shelf sediments, and fish from the Shelf are contaminated with high levels of DDT and PCBs. Generally speaking, contaminant levels are highest in bottom-feeding fish such as the white croaker and are significantly lower in fish that live higher up in the water column. DDT levels in ocean waters over the site range from 0.6 to 15.8 ng/L, while PCBs range from 0.06 to 1.14 ng/L. These levels all exceed the California Ocean Plan standards for DDT and PCBs. DDT levels in samples from a reference station upcurrent from the Palos Verdes Shelf were 0.20 ng/L, while PCBs were not detected. While DDT and PCBs at the PV Shelf site do not pose a risk for swimming and other types of water contact recreation, they are present at unsafe levels in some fish.

California EPA’s Office of Environmental Health Hazard Assessment (OEHHA) has issued updated health warnings for consumption of certain fish off Palos Verdes and other Southern California sites in 2009. The initial sport fish consumption advisory has been included in the California sport fishing regulations since March 1992. In 1990, the California Department of Fish and Game closed commercial fishing of white croaker on the Palos Verdes Shelf and nearby areas due to health risks posed by DDT and PCB contamination. Commercial fishing for other species of fish is permitted. A 1997 study by Heal the Bay of contaminant levels in commercially sold white croaker raised serious questions about the effectiveness of the fishing ban in terms of both the area closed and enforcement of the ban. In 1998, the Department of Fish and Game established a bag limit for white croaker to address the concern that sport fishermen may be illegally selling their white croaker catch to markets.

Ecological risks are being evaluated for a variety of assessment endpoints, including the benthic macroinvertebrate community, demersal (bottom-dwelling) and pelagic (water column) fish, fish-eating birds, raptors (such as bald eagles) and marine mammals. The results to date indicate that existing concentrations of DDT and PCBs in sediments on the Palos Verdes Shelf continue to pose a risk to benthic organisms, to fish (particularly demersal fish) and to fish-eating birds and raptors.

Investigation and Cleanup Activities

In 1990, the federal and state natural resource trustees began a natural resource damage assessment for the Southern California Bight, which includes the Palos Verdes Shelf. Following a review of the Trustees' 1994 expert reports, EPA in July 1996 initiated a Superfund non-time critical removal action to evaluate the need for and feasibility of actions to address human health and ecological risks.

In July 1997, EPA completed the Screening Evaluation of Response Actions for Contaminated Sediment on the Palos Verdes Shelf. That document looked at several potential remediation technologies and determined that the most feasible response technology was in situ (in place) capping (possibly augmented by institutional controls). In March 2000, EPA completed the Engineering Evaluation/Cost Analysis (EE/CA) report for Palos Verdes Shelf that summarizes site risks and evaluates the potential response actions. Based on the EE/CA report, EPA issued a Proposed Plan (see Community Involvement section below) that recommended institutional controls (public outreach & education, monitoring and enforcement) as an initial response actions to address human health risks associated with the consumption of contaminated fish.
As part of the EE/CA report, the U.S. Army Corps of Engineers Waterways Experiment Station (WES) performed an evaluation of in-situ capping options for EPA. The WES report is available via their web site at http://el.erdc.usace.army.mil/elpubs/pdf/trel99-2.pdf . Based on the WES report, EPA conducted a pilot capping project in 2000 in a small area of the site to evaluate cap placement methods and short-term impacts of cap construction. See below to view the October 2002 fact sheet that summarizes the pilot capping project. In 2002, EPA concluded that cap construction would be technically feasible; however, additional studies were needed. In 2004, EPA conducted several data gap studies to better understand the sediment fate and transport and the stability of the cap. Based on the results of these data gap studies, EPA completed the Remedial Investigation Report for the site in October 2007 and the Feasibility Study in May 2009. In September 2009, EPA signed the Interim Record of Decision which selected capping, monitored natural recovery, and institutional controls as the interim remedial action for Palos Verdes Shelf.

The natural resource trustee agencies are addressing restoration of natural resource damages through the Montrose Settlements Restoration Program (MSRP). The MSRP is responsible for planning and implementing restoration projects to benefit injured natural resources such as bald eagles and peregrine falcons, and to create improved recreational and subsistence fishing opportunities to offset the impairment of fishing caused by contamination present in sports fish caught off the coast of Southern California. MSRP project updates is available via their website site at http://www.montroserestoration.noaa.gov/

Initial Actions

EPA issued the Action Memorandum for institutional controls in September 2000 and it can be downloaded from Region 9's web page. The web address is http://www.epa.gov/Region9/superfund/pvshelf/ and is called "Region09: Cleaning up the Palos Verdes Shelf."

The institutional controls program has three major elements: public outreach and education, fish monitoring, and enforcement. The public outreach and education program is being implemented by EPA in collaboration with several federal, state and local agencies, environmental groups and community-based organizations. To facilitate coordination and cooperation among these entities, EPA created Fish Contamination Education Collaborative, which guides the implementation of EPA's PV Shelf programs. EPA and its key stakeholders have been carrying out strategic planning of the Palos Verdes Shelf Institutional Controls Program since 2004. For more information on the Fish Contamination Education Collaborative is available on http://www.pvsfish.orgThe fish monitoring program involves sampling both fish in the ocean and fish in retail markets. The MSRP and EPA completed the ocean fish sampling program in July 2007. EPA utilized the data to update the risk assessments for the site. EPA and the public are currently awaiting the State of California to update the existing fish advisory based on the recent data. EPA continues to monitor white croakers at local markets since 2004. Finally, California Department of Fish and Game and local county health departments are carrying out enforcement and education activities under partnership with EPA, including marketplace inspection and white croaker recreational fishing bag limit and white croaker commercial catch ban inspection.

EPA established the Fish Contamination Education Collaborative (FCEC) to educate the public on the health risks posed by chemically contaminated fish and to encourage the public to adopt safer fish consumption practices.

The cornerstone of the FCEC is the partnership between federal and state government agencies, local health departments, community based organizations, and other local institutions. The goal of the program is to conduct education for the most affected populations, so they can make informed decisions about fish contamination issues. The outreach efforts have been conducted in English, Spanish, Cambodian, Chinese, Filipino, Korean, Vietnamese, Chamorro, Samoan, Marshallese and Tongan.

The current program focus is to measure risk reduction through the ICs program implementation. EPA, with assistance from all stakeholders, put together a road map for the Institutional Controls Program which outlines the numeric objectives and associated strategies and tactics for the program. The document is available at http://www.pvsfish.org.

Site Studies

Remedial Investigations/Feasibility Study Update

In 2000, EPA conducted a pilot capping study project over a small area of the PV Shelf site. Three 45-acre areas at different depths were capped with sand from two different areas, using different capping methods. Post-cap monitoring in 2002 showed that contaminant levels over the capped areas were comparable to uncapped areas. The post-capping report identified additional information that was needed to evaluate the potential viability of capping. The EPA conducted four studies to address these data gaps and to learn more about the site. The studies are described below:

1.) The geotechnical study consisted of collecting sediment cores and performing a sonar survey. The sediment cores were analyzed for erodibility and geotechnical properties, such as grain size, bulk density, and total organic carbon. These studies provide information about the sediments’ erosion potential and other sediment characteristics throughout the site. The final report is available under "Site Documents and Reports" on the following link: http://www.epa.gov/region09/superfund/pvshelf

2.) The large bioturbator study collected samples at 19 stations in the sediments to study the extent of sediment mixing caused by ocean-dwelling creatures, including large species that could burrow through a sand cap and/or mix sediment from the deeper, more contaminated areas, with the cleaner top sediment layer. The study provided an assessment of the extent of sediment mixing that occurs on the Shelf due to these species. The study found evidence of large bioturbators, especially in the northwest region of the site; however, the populations were low to average and were not responsible for the recontamination found on the caps. The final report is available under "Site Documents and Reports" on the following link: http://www.epa.gov/region09/superfund/pvshelf

3.) The resuspension study looked at one of the pilot caps placed in 2000. In 2001 the Los Angeles County Sanitation District collected sediment cores across the PV Shelf and noted that the peak concentration of contaminated sediment was closer to the surface along the edge of one of the pilot caps. This study took sediment cores across the cap to assess the extent to which cap placement may have displaced the upper layer of less contaminated sediment, thereby bringing the more contaminated layer closer to the surface. This study found evidence of sediment displacement, but was unable to gauge the extent of it. It appeared that the capping technique caused the displacement. The final report is available under "Site Documents and Reports" on the following link: http://www.epa.gov/region09/superfund/pvshelf

4.) The oceanographic study focused on learning more about the tides and currents around the PV Shelf. Equipment that measures currents, turbidity, temperature and other factors was anchored on the Shelf from February to July 2004. This study provided the EPA with additional data; however, it only captured one storm event, leaving unanswered questions about the magnitude and frequency of oceanographic processes that resuspend and transport PV Shelf sediment. As a result, EPA funded an additional oceanographic study that ran from December 2007 to April 2008. This study captured three major storms and collected data on ocean conditions that can be used in modelling sediment transport.

Remedial Investigation Report

These four studies were completed in 2004. Data analysis and report preparation took place in 2005. The geotechnical, sediment displacement and bioturbation reports have been finalized. A draft oceanographic data report has been prepared; however, as mentioned above, additional work is needed to determine if the effluent-affected deposit will erode. Nevertheless, information from these and earlier studies were used to prepare the Remedial Investigation (RI) Report. The RI Report (October 2007) has been finalized and a copy is posted on “Site Documents and Reports.” The RI Report discusses the nature and extent of contamination on the PV Shelf and the transport and fate of the contaminants. The RI report also discusses levels of DDT and PCBs that birds, animals, and people may be exposed to through consumption of fish and other creatures found on the PV Shelf.

Feasibility Study

The Feasibility Study (FS) built on the findings of the 2004 field studies and the Remedial Investigation Report. The FS analyzed cleanup strategies for the Shelf, including dredging, natural recovery, capping, and in situ and ex situ treatment. The FS determined capping and monitored natural recovery are the most feasible alternatives, i.e., most effective at reducing the human health and ecological risk posed by the site. The FS analyzes in detail three alternatives, including no action, using nine criteria required by law. The Feasibility Study is available on-line.

Proposed Plan/Record of Decision

EPA presented its Proposed Plan that includes the remedial cleanup alternatives evaluated, and identifies EPA’s preferred alternative for the PV Shelf site. The public comment period was from June 15 to July 15, 2009. Three public meetings were held from June 23rd through June 25th at the; Cabrillo Beach House in San Pedro, CA; Banning's Landing in Wilmington, CA; and Palos Verdes Library in Rolling Hills Estates, CA. The Proposed Plan was mailed to the Site's mailing list, sent to the information repositories and posted on the website. EPA also met informally with many interested stakeholder groups. Comments received through this period are included in the Record of Decision (ROD) under Responsiveness Summary. The ROD is a document that memorialize EPA's interim decision.

Remedy Selected

Record of Decision

On September 30, 2009, the EPA signed an interim Record of Decision (ROD) that selected an initial remedial action for PV Shelf of capping, monitored natural recovery, and institutional controls.

Remedy Design

Remedial Design

In support of the capping and monitored natural recovery components, EPA conducted a Baseline Sediment Study in 2009. Surprisingly, these results indicate that an interim sediment cap may be unnecessary since the post cap installation sediment goals for DDTs and PCBs appear to have been achieved. Therefore, EPA suspended the sediment cap design efforts. Below is a comparison of the Interim Record of Decision goals and the 2009 Sediment Study results:

Constituents

Interim Record of Decision Goals

2009 Sediment Study Results

Mean DDT Concentration

78 mg/kg organic carbon (OC)

56 mg/kg OC

Mean PCBs Concentration

7 mg/kg OC

0.23 mg/kg OC

EPA is currently investigating theories such as natural dechlorination, biodiffusion from sediment into the water column, and sediment transport as possible causes of the improved conditions.

As part of the investigation, EPA is conducting another sampling study at the site with input from government technical advisors, local government agencies, and environmental groups. This Study will:
· Collect and analyze sediment samples from all the 2009 sediment sampling locations plus 10 additional stations.
· Collect and analyze water column samples
· Collect and analyze White Croaker and Barred Sand Bass fish tissue samples

In addition, EPA is also awaiting the results from fish tissue, sediment movement, and DDT de-chlorination studies being conducted by other government agencies and universities on behalf of EPA. Along with the water column, sediment flux, fish tracking, and the 2009 Sediment Study, the results of these studies will improve our understanding of the Site and the relationship between sediment and fish contamination and support the remedial design for the site. EPA expects to receive the completed studies late 2016.

Depending on the results of the investigation, EPA may re-evaluate the selected interim remedy or simply reinitiate the cap design.

Cleanup Ongoing

Remedial Action

EPA continues to implemented the institutional controls component of the remedy. With the assistance of the local government agencies, universities, none profit community groups, and California Fish and Wildlife, EPA continues to: 1) implement existing public outreach and education efforts to increase awareness and understanding of the existing fish consumption advisories and fishing restriction, 2) evaluate and track contaminant concentrations in fish (mainly white croaker) caught at or near the site as well as those sold in retail fish markets and served in restaurants, 3) Enforce the existing commercial and recreational restrictions on white croaker fishing established by the California Department of Fish and wildlife.

Cleanup Results to Date

First Five Year Review Report: On August 28, 2014, EPA completed the first Five Year Review Report for Palos Verdes Shelf. The report concluded that "the interim remedy at Montrose Chemical Corporation Operable Unit 5 (Palos Verde Shelf) is protective of human health and the environment. Institutional controls are in place and are effective in protecting users of PV Shelf. Results of sampling programs and research by EPA and others indicate that natural recovery processes are occurring. While the necessity of an isolation cap is further assessed, the combination of institutional controls and monitored natural recovery is effective and is progressing towards attaining the specific interim cleanup goals and timelines set forth in the Interim Record of Decision."

The most complete collection of documents is the official EPA site file, maintained at the following location:

Superfund Records Center

Mail Stop SFD-7C

95 Hawthorne Street, Room 403

San Francisco, CA 94105

(415) 820-4700

Enter main lobby of 75 Hawthorne street, go to 4th floor of South Wing Annex.

Additional Links

The Fish Contamination Education Collaborative (http://www.pvsfish.org) is part of EPA's ongoing public outreach and education efforts to address risks associated with consumption of contaminated fish.